The integrated circuit (IC) industry has experienced exponential growth. Technological advances in IC materials and design have produced generations of ICs, where each generation has smaller and more complex circuits than the previous generation. In the course of IC evolution, functional density (i.e., the number of interconnected devices per chip area) has generally increased while geometry size (i.e., the smallest component (or line) that can be created using a fabrication process) has decreased. This scaling down process generally provides benefits by increasing production efficiency and lowering associated costs.
Such scaling down has also increased the complexity of processing and manufacturing ICs. For example, while three-dimensional fin-like field effect transistors (FinFET) are desirable for many of today's IC applications, their decreased feature sizes also pose challenges in device fabrication. In one example, shortened channel lengths may lead to lowered barrier for diffusion of active dopant species out of source/drain features, which may compromise device performance. As such, improvements in this area are needed.